AbstractThis unit describes various protocols for the isolation and purification of the main constituents of microtubules, chiefly α‐ and β‐tubulin, and the most significant microtubule associated proteins (MAPs), specifically MAP1A, MAP1B, MAP2, and tau. We include a classical isolation method for soluble tubulin heterodimer as the first basic purification protocol. In addition, we show how to analyze the tubulin and MAPs obtained after a phosphocellulose chromatography purification procedure. This unit also details a powerful and simple method to determine the native state of the purified tubulin based on one‐dimensional electrophoresis under nondenaturing conditions (UNIT 6.5). The last protocol describes the application of a new technique that allows visualizing the quality of polymerized microtubules based on atomic force microscopy (AFM). Curr. Protoc. Cell Biol. 39:3.29.1‐3.29.28. © 2008 by John Wiley & Sons, Inc.